Using a relatively cheap lux meter and THIS table, can't you calculate the approximate power of a laser if you have it's wavelength and lux? It will probably not be as accurate as a LPM but certainly a cheaper solution!
If you had such table for specific luxmeter, we could talk. The meter would have to be able to measure whole output of the laser though. It it only had small sensor, and you put 2W of 445nm into it, I bet most luxmeters would just smoke a bit and die.
It would be simple to compare lasers though. If you had one calibrated/trusted laser with same wavelength as tested laser, you might even compare their brightness indirectly, like shining at wall at night and measuring the reflected light at some distance.
Using a relatively cheap lux meter and THIS table, can't you calculate the approximate power of a laser if you have it's wavelength and lux? It will probably not be as accurate as a LPM but certainly a cheaper solution!